1、什么是拦截器
Spring MVC中的拦截器（Interceptor）类似于Servlet中的过滤器（Filter），它主要用于拦截用户请求并作相应的处理。例如通过拦截器可以进行权限验证、记录请求信息的日志、判断用户是否登录等。在SpringMVC中通过实现HandlerInterceptor接口实现自定义拦截器类。
2、 拦截器案例
（1）MyIntercept
package com.springmvc.intercept; import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView; import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class MyIntercept implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
System.out.println("=========拦截器当中的handle方法=========");
return true;
} @Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("=======在HandlerAdapter之后执行，在DispatcherServlet解析视图之前执行=====");
} @Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("=========呈现之后调用=========");
}
}
代码实现
（2）拦截器配置spring-mvc.xml
<!--利用default-servlet放行资源-->
<mvc:default-servlet-handler/> <!--配置拦截器-->
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/my/**"/>
<bean class="com.springmvc.intercept.MyIntercept"></bean>
</mvc:interceptor>
</mvc:interceptors>
代码实现
（3）MyController
@Controller
@RequestMapping("/my")
public class MyController {
@RequestMapping("/doFirst")
public String doFirst(){
System.out.println("=========控制器中的方法=========");
return "index";
}
代码实现
（4）控制台效果
3、Spring MVC的数据校验
3.1 数据校验案例
（1）导入依赖
<!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-validator -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.4.1.Final</version>
</dependency>
代码实现
（2）validate.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>测试案例</title>
</head>
<body>
<form action="/my/validate" method="post">
编号：<input type="text" name="uid"/><br/>
姓名：<input type="text" name="uName"/><br/>
邮箱：<input type="text" name="email"/><br/>
电话：<input type="text" name="phone"/><br/>
身份证号：<input type="text" name="userCode"/><br/>
<input type="submit" value="提交"/>
</form>
</body>
</html>
代码实现
（3）实体类UserInfo
package com.springmvc.entity; import org.hibernate.validator.constraints.Email;
import org.hibernate.validator.constraints.Length; import javax.validation.constraints.NotNull;
import javax.validation.constraints.Pattern; public class UserInfo { @NotNull(message="编号不能为空")
private Integer uid; @NotNull
@Length(min = 2,max = 8,message = "用户名不能少于2位或大于8位")
private String uName; @Email(message = "邮箱格式不正确")
private String email; @Pattern(regexp = "/^1[3456789]\\d{9}$/",message = "手机号式不正确")
private String phone; @Pattern(regexp = "/(^\\d{15}$)|(^\\d{18}$)|(^\\d{17}(\\d|X|x)$)/",message = "身份证号格式不正确")
private String userCode; public Integer getUid() {
return uid;
} public void setUid(Integer uid) {
this.uid = uid;
} public String getuName() {
return uName;
} public void setuName(String uName) {
this.uName = uName;
} public String getEmail() {
return email;
} public void setEmail(String email) {
this.email = email;
} public String getPhone() {
return phone;
} public void setPhone(String phone) {
this.phone = phone;
} public String getUserCode() {
return userCode;
} public void setUserCode(String userCode) {
this.userCode = userCode;
}
}
代码实现
（4）MyController
package com.springmvc.controller; import com.springmvc.entity.UserInfo;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.annotation.RequestMapping; import javax.validation.Valid;
import java.util.List; @Controller
@RequestMapping("/my")
public class MyController {
@RequestMapping("/doFirst")
public String doFirst(){
System.out.println("=========控制器中的方法=========");
return "index";
} @RequestMapping("/validate")
public String Validate(@Valid UserInfo info, BindingResult bindingResult){
//如果有异常信息
if (bindingResult.hasErrors()){
//获取异常信息对象
List<ObjectError> allErrors = bindingResult.getAllErrors();
//将异常信息输出
for (ObjectError errors:allErrors) {
System.out.println(errors.getDefaultMessage());
}
}
return "index";
}
}
代码实现
（5）效果展示
